I am trying to assign new UV coordinates to a face via python and have a problem: after writing my UV data nothing happens, blender does not see or recognize the changes I make. when rerunning the script the old values are there again.

here's a small piece of code:

import Blender

mesh = Blender.NMesh.GetRawFromObject('Plane')

face = mesh.faces[0]

# that prints me the original uv data as set manually in the UV editor
print face.uv